procedure TFrmOrderBy.BtnOrderClick(Sender: TObject);
     var
      i: integer;
      fieldname: string;
     begin
      with AQuery do
       begin
         Close;
         SQL.Clear;
         SQL.Add('SELECT max(datalength(id)) AS id ,');
         SQL.Add('max(datalength(number))AS number,');
         SQL.Add('max(datalength(name))AS name,');
         SQL.Add('max(datalength(old))AS old,');
         SQL.Add('max(datalength(sex))AS sex,');
         SQL.Add('max(datalength(telephone))AS telephone,');
         SQL.Add('max(datalength(department))AS department,');
         SQL.Add('max(len(joindate))AS joindate');
         SQL.Add('FROM TB_Worker');
         Open;
       end;
      for i := 0 to DBGList.Columns.Count - 1 do
       begin
         fieldname := DBGList.Columns[i].Field.FieldName;
         DBGList.Columns[i].Field.DisplayWidth := AQuery.FieldByName(fieldname).AsInteger;
       end;
     end;